The present invention relates to a multi-lobed electrical winding, such as those for the stator of an alternator, particularly for use in the automotive field and of the type comprising turns defining a star-shaped configuration having a plurality of radial lobes alternated with hollows.
Methods and apparatus for forming a multi-lobed winding for the stator of an alternator are disclosed, for example, in Italian Patent No. 1,157,040, which corresponds to Barrera U.S. Pat. No. 4,512,376, entitled Apparatus For Forming Stator Coils Of Dynamo Electric Machines. Both patents are incorporated herein by reference.
Typically, in the case of a three-phase alternator for automotive use, each stator is provided with a winding including three multi-lobed coils angularly shifted relative to each other. The coils are formed at different stages by a forming machine, and each coil has two wire terminal ends. Each of the three multi-lobed coils constituting one of the three phases of the winding is split into two semi-coils or semi-phases which are angularly shifted by one lobe relative to each other, so that the lobes of one semi-phase are opposite the hollows between the lobes of the other semi-phase.
As is known in the art, the two semi-phases of each coil are made by a forming machine at two subsequent stages by cutting the supplied wire between one forming stage and the other. Each semi-phase of the three winding phases of a finished winding inserted into a stator therefore has a pair of terminal ends. This results in a total of twelve terminal ends.
A stator winding of undulatory type with a single continuous wire, including two multi-lobed coils shifted relative to each other by one lobe, has already been proposed. (See, e.g., Taji et al. U.S. Pat. No. 4,857,787, entitled Armature Of A.C. Generator For A Car And Method Of Manufacturing The Same, and corresponding European Patent No. 209,091, both of which are incorporated herein by reference). This method initially involves forming a single multi-lobed coil which is then split into two coils, without cutting the wire portion connecting them, one of the coils being overlapped on the other in an overturned position. This additional operation wastes time and accordingly decreases the productivity of the machine.
In view of the foregoing, it would be desirable to provide a method and apparatus in which the final required configuration of the winding is obtained without additional operations after winding the wire by an apparatus which requires very small changes with respect, for example, to the apparatus taught in Italian Patent No. 1,157,040 and corresponding U.S. Pat. No. 4,512,376.
It would also be desirable to provide a method and apparatus for forming a multi-lobed winding for the stator of an alternator which enable the two semi-phases of each winding phase to be made continuously, without cutting the wire at the end of the forming operation of the first semi-phase, so as to simplify the operations necessary for forming the winding, as well as to obtain a finished winding with a low number of terminal ends.
It would further be desirable to provide a method and apparatus by which multi-lobed windings constituted by a plurality of coaxial superimposed multi-lobed coils having their lobes angularly shifted relative to each other can be obtained continuously.
It is an object of the present invention to provide a method and apparatus in which the final required configuration of the winding is obtained without additional operations after winding the wire by an apparatus which requires very small changes with respect, for example, to the apparatus taught in Italian Patent No. 1,157,040 and corresponding U.S. Pat. No. 4,512,376.
It is also an object of the present invention to provide a method and apparatus for forming a multi-lobed winding for the stator of an alternator which enable the two semi-phases of each winding phase to be made continuously, without cutting the wire at the end of the forming operation of the first semi-phase, so as to simplify the operations which are necessary for forming the winding as well as to obtain a finished winding with a low number of terminal ends.
It is further an object of the present invention to provide a method and apparatus by which multi-lobed windings constituted by a plurality of coaxial superimposed multi-lobed coils having their lobes angularly shifted relative to each other can be obtained continuously.
These and other objects and advantages of the invention are accomplished by forming a multi-lobed winding for the stator of an alternator. In a first stage, a first multi-lobed coil is formed by winding a continuously fed wire in a first direction. In a second stage, a second multi-lobed coil, axially superimposed to the first coil, is formed without cutting the wire being fed by winding the wire in the opposite direction and arranging the second coil at a position angularly shifted relative to the first coil. The second coil has its lobes at the same angular positions as the hollows of the first coil. The wire portion connecting the two coils is bent where the wire reverses its winding direction so as to form a loop, the loop following an annular path matching the profile of a lobe of one of the two coils for one part and the profile of a hollow of the other coil opposite the lobe for another part.
The invention thus provides a multi-lobed winding for the stator of an alternator, particularly for use in the automotive field and of the type comprising turns defining a star-shaped configuration having a plurality of radial lobes alternated with hollows.
The invention also provides a winding comprising two coaxial superimposed multi-lobed coils with lobes angularly shifted relative to each other. There is no interruption of the wire constituting the winding and, therefore, the winding has only two terminal ends. Thus, the method and apparatus according to the invention simplify the forming operation as well as provide a stator winding with a number of terminal ends reduced by a factor of two.